Air preheater for furnaces



2 Sheets-Sheet l L. T. MART AIR PREHEATER FOR`FURNACES Filed May 23, 41925 Dec. 18, 1928.

" A 1,695,434 L. T. MART Y .un PREHEATER Fon FunNAcEs 4 ljilgaway 23, 1925 2 sheets-sheet 2 Patented Dec. 18, 1928.

LEON T. MART, orKANsAs crrY, MISSOURI.

' AIR PREHEATER non FURNAcEs.

Application led May 23, 1925. .Serial No. 32,522.

My invention relatesto air pre-heaters, for f utilizing the sensible heat influe gases that have felt a furnace topreheat the air supplied to the furnace for combustion.

While applicableto many different types of furnaces I regard the widestapplication of my invention-to be in preheating the air supply of distillation furnaces, and for this reason have illustrated my invention in connection with this type of furnace.

My invention relates more particularly to the supporting and sealing structure at top A and bottom of air tubes across a hot flue.

A purpose of my invention is to draw the `air supply for a furnace through metal tubes (preferably substantially verticaltubes) that have major portions within a het flue to a chimney and to provide quick, simple and cheap means for seating and sealing the pipes.

A further purposeis to rest the pipes in. sealing engagement with aclosurel plate at their lower ends and to seal about the pipe at the upper ends by heat insulation. y

Further purposes will appear' in the specication and in the claims.

I prefer to illustrate my invention by one general form only with a slight modification among the various forms and modifications which may appear, selecting a form which is simple, practical and inexpensive and which at the same time well illustrates the principles of my invention. y

Figure 1 is a longitudinal section through a furnace and chimney embodying my invention.

Figure 2 is a section of Figure 1, taken upon the line 2-2.

Figure 3 is an` enlarged fragmentary section of Figure 2, taken upon the line 3 3.

Figure 4 is a section of Figure Staken upon the line 4 4.

Figure 5 is an enlarged fragmentary sec-Y tional detail illustrating my invention.

Figure 6 is a section corresponding to Figure 5 but showing a modification.

Like numerals refer to like'parts in all figures.

Referringto the drawingsand describing in illustration and not in limitation z- The boiler or still 10 is shown conventionally and may be any yone of many different types. It is shown supported by stirrups 11 riveted to the shell and as resting upon opposite walls 12 and 13 of a furnace 14.

vThe boileris charged through a supply pipe 15,` and the distillation products leave the top of the boiler through apipe 16. Man- .i hole 17 is shown at one end to permit'ventilation and entry when the boiler is opened up for cleaning.

The top and ends of the boiler are shown covered with insulation 18. The iirebox beneath the furnace has a fuel f supply (here presumed to be oil) at 19, suitable air inlet 20aud hot flue 21 to chimney 22.

I utilize the hot flue 21 to preheat the air supply. For this purpose -I roof and floor a portion of the flue with one vor more ypairs of. transverse metal Vplates 23, 24, respectively (preferably of cast iron) ,supporting the airpreheating tubes 25 on and in these plates.

Each upper plate 23 is bored at 26-to loosely l pass the air tubes down from the top and th'o corresponding lower plate is Vboredand counterbored at 27 and 28 in registry with the holes at l26 to receive and seat the lower ends of the tubes.. n f

The form of yseats used at the lower ends of the tubes may comprise various forms of which I show a bore and counterbore fitting the straight end of a tube, as shown in Figures 4 and 5 and in Figure 6 a tapered hole fitting th) correspondingly tapered lower end of the tu e.

In the form shown in Figure 5, the tubes are straight lengths of pipe, uniform throughout their length and without any machining at either end, furth-er than to remove any burr incident to cutting them to length.

The bore 27 and counterbore 28 in the lower plate to provide a sealing seat for the lower end of the tube, are respectively of thek inside and outside diametersl of the tube, the end of the tube resting upon the annular shoulder 29 formed by the counterbore.

Obviously a somewhat more perfect fit and seal may be obtained my machining the lower end of the tube to lit a definite perforation in the plate. This is illustrated in Figure `6 where the lower end of the tube has been machined to make taper lit at 30 with a taperedv hole 31 through the lower plate.

Where machining is to be resorted to, the taper fit seat of Figure 6 offers some advantages over the fit shown in Figure 5; however the seat obtained by the structure in Figure 5 may be suiiicient and its cheapness and The upper ends 3:2 of the tubes 25 extend a distance above the plate 23 and a bed of insulating material 33, preferably iireclay, is placed on top of the plate around the open ends of the tubes.

et heat insulating the top ot the flue roin the rooni. ,e Y i Y The duct 34 Carrying the preheated air from the lower ends ont the tubes to the air inlet 201s preferably runl under the furnace so sealinrf therewithtransversely to the: axes as to be out ot the Way.

The upper ends oi the tubes 25 open into the roo1n,ia.nd` in operation tlieair supplyitor the furnace is drawn troni the furnace rooin through the hot tubes and the duct 2O to the iurnace. The tubes are `preferably,placed in staggered rowsacross the iiue, as seen in Figure 3, so that the hot products or coinbustion have. to travel tortuously to pass thein, and i none ot the Jtubes are in any wise shielded troni these hot gases by any ot trie other tubes.

A'notuble feature-otiny` .invention is the einv treinc easelivith which ieplaceii'ients n'iay Vbe niade. The, tubes gradually burn out and when they do, replacement is incr-ely a niatter oi' pulling out the ifaulty tubes and putting;` in new ones, using a little ireclay to ircshly seal tliein around the top.

In view oi iiiy invention and disclosure, variations and inodiiications to ineet individual whim or particular' need Willidoubtless.

This bed ot insulation-` serves t-he double purpese ot allor-ding aneasy and effective seal around the ends of the tubes Where they pass through the upper plate `aridi-i I claiin as new and desire to secure by Letters Patent is l., ln apreheater `for heating inlet air by flue gases, a flue :tor heated gases, having top and bot-toni plates apertured to communicate respectively with. tlieatinospheie and With a passage for preheated air supply, the aper turesiinltheubottoin plate being tapered in combination With tubes passing through one setoft,aperturcs,.crossing the flue and pressing longitudinally against the tapered part or' the Wall about the other set oi' apertures, ,pressing thereagainst by reason of Weight Valone and u of the tubes. i i

2. in a preheater ior heating` inlet air by luegases, a flue lor heated gases having'opposite plates apertured respectively in coininunication with r the atmosphere andivitli'a i preheated air passage,.the fornier` aperturingg.` being li er Vthan thelatter, and both' stag: gered, ii'iiiconibination WithA tubes passing` through the larger apertures, havingztapered,A lower ends andiitting longitudinallyiagainsti. the `wall having the siiialler apertures, iniline` vri'th said apertures, so that the' tightness ,oi ht laterally increases with the pressure.`

the larger, in combination With tubes. passing through' the apertures in the upper Wall and. i

extending above its apertures and a covering` oil' heat insulation sealing material between the tube extensions and the apertures in the i upper Wall;

Liioisr` T. Mann 

